971 research outputs found
Collective T=0 pairing in N=Z nuclei? Pairing vibrations around 56Ni revisited
We present a new analysis of the pairing vibrations around 56Ni, with
emphasis on odd-odd nuclei. This analysis of the experimental excitation
energies is based on the subtraction of average properties that include the
full symmetry energy together with volume, surface and Coulomb terms. The
results clearly indicate a collective behavior of the isovector pairing
vibrations and do not support any appreciable collectivity in the isoscalar
channel.Comment: RevTeX, two-column, 5 pages, 4 figure
DXA-derived hip shape is related to osteoarthritis:findings from in the MrOS cohort
BF conducted this research whilst on a clinical research primer fellowship awarded by the Elizabeth Blackwell Institute, University of Bristol, UK. This study was funded by Arthritis Research UK project grant ref 20244. CG is funded by Arthritis Research UK grant ref 20000. The Osteoporotic Fractures in Men (MrOS) Study is supported by National Institutes of Health funding. The following institutes provide support: the National Institute on Aging (NIA), the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), the National Center for Advancing Translational Sciences (NCATS), and NIH Roadmap for Medical Research under the following grant numbers: R01 AR052000, K24 AR048841, U01 AG027810, U01 AG042124, U01 AG042139, U01 AG042140, U01 AG042143, U01 AG042145, U01 AG042168, U01 AR066160, and UL1 TR000128.Peer reviewedPostprin
Superselection Sectors and General Covariance.I
This paper is devoted to the analysis of charged superselection sectors in
the framework of the locally covariant quantum field theories. We shall analize
sharply localizable charges, and use net-cohomology of J.E. Roberts as a main
tool. We show that to any 4-dimensional globally hyperbolic spacetime it is
attached a unique, up to equivalence, symmetric tensor \Crm^*-category with
conjugates (in case of finite statistics); to any embedding between different
spacetimes, the corresponding categories can be embedded, contravariantly, in
such a way that all the charged quantum numbers of sectors are preserved. This
entails that to any spacetime is associated a unique gauge group, up to
isomorphisms, and that to any embedding between two spacetimes there
corresponds a group morphism between the related gauge groups. This form of
covariance between sectors also brings to light the issue whether local and
global sectors are the same. We conjecture this holds that at least on simply
connected spacetimes. It is argued that the possible failure might be related
to the presence of topological charges. Our analysis seems to describe theories
which have a well defined short-distance asymptotic behaviour.Comment: 66 page
Band structure of 235 U
Over a period of several years we have performed three separate experiments at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron in which 235U (thick target) was Coulomb-excited. The program involved stand-alone experiments with Gammmasphere and with the 8pi Spectrometer using 136Xe beams at 720 MeV, and a CHICO-Gammasphere experiment with a 40Ca beam at 184 MeV. In addition to extending the known negative-parity bands to high spin, we have assigned levels in some seven positive-parity bands which are in some cases (e.g., [631]1/2, [624]7/2, and [622]5/2) strongly populated by E3 excitation. The CHICO data have been analyzed to extract E2 and E3 matrix elements from the observed yields. Additionally, many M1 matrix elements could be extracted from the Îł-ray branching ratios. A number of new features have emerged, including the unexpected attenuation of magnetic transitions between states of the same Nilsson multiplet, the breakdown of Coriolis staggering at high spin, and the effect of E3 collectivity on Coriolis interactions
Search for flavor-changing neutral currents and lepton-family-number violation in two-body D0 decays
Results of a search for the three neutral charm decays, D0 -> mu e, D0 -> mu
mu, and D0 -> e e, are presented. This study was based on data collected in
Experiment 789 at the Fermi National Accelerator Laboratory using 800 GeV/c
proton-Au and proton-Be interactions. No evidence is found for any of the
decays. Upper limits on the branching ratios, at the 90% confidence level, are
obtained.Comment: 28 pages, 18 figures. Submitted to Physical Review
Empirical investigation of extreme single-particle behavior of nuclear quadrupole moments in highly collective AâŒ150 superdeformed bands
The intrinsic quadrupole moment Q0 of superdeformed rotational bands in AâŒ150 nuclei depends on the associated single-particle configuration. We have derived an empirical formula based on the additivity of effective quadrupole moments of single-particle orbitals that describes existing measurements from 142Sm to 152Dy. To further test the formula, the predicted Q0 moments for two superdeformed bands in 146Gd of 14.05eb were confronted with a new measurement yielding 13.9±0.4eb and 13.9 ± 0.3eb, respectively. This excellent agreement provides empirical evidence of extreme single-particle behavior in highly deformed, collective systems
Homeostatic apoptosis prevents competition-induced atrophy in follicular B cells
While the intrinsic apoptosis pathway is thought to play a central role in shaping the B cell lineage, its precise role in mature B cell homeostasis remains elusive. Using mice in which mature B cells are unable to undergo apoptotic cell death, we show that apoptosis constrains follicular B (FoB) cell lifespan but plays no role in marginal zone B (MZB) cell homeostasis. In these mice, FoB cells accumulate abnormally. This intensifies intercellular competition for BAFF, resulting in a contraction of the MZB cell compartment, and reducing the growth, trafficking, and fitness of FoB cells. Diminished BAFF signaling dampens the non-canonical NF-ÎșB pathway, undermining FoB cell growth despite the concurrent triggering of a protective p53 response. Thus, MZB and FoB cells exhibit a differential requirement for the intrinsic apoptosis pathway. Homeostatic apoptosis constrains the size of the FoB cell compartment, thereby preventing competition-induced FoB cell atrophy.StĂ©phane Chappaz, Kate McArthur, Liam Kealy, Charity W. Law, Maximilien Tailler, Rachael M. Lane ... et al
Does the engineering culture in UK higher education advance womenâs careers?
Current research suggests that increases in the number of women studying engineering and related courses have not been matched by a similar increase in women engineering professionals. This suggests that although women are attracted to engineering, their experiences in higher education (HE) discourage them from pursuing their chosen career path. The paper explores whether the masculine culture of the engineering sector permeates the culture and curriculum in engineering HE, and if it does, what impact this has on women engineering students. This is achieved through semi-structured, qualitative interviews with a range of female engineering students from both the pre and post 1992 university sectors. Findings indicate that while women are not deterred from pursuing their chosen engineering career, the culture and structure of the engineering education system has been designed for a male audience. This suggests that engineering HE does not benefit most female students to the same extent as male students. It is recommended
that HE engineering must review its structure, culture, practices and curriculum if it is to retain female engineering graduates and to attract more women into the sector. This paper fulfils an identified gap in research on women in engineering and will be of interest to university engineering departments and faculties and the Engineering Council, as well as to those in the fields of social policy, education and equal opportunities
High-spin isomers and three-neutron valence configurations in 211Pb
Deep-inelastic reactions between a beam of 1360 MeV 208Pb ions and a thick 238U target have been used to populate the neutron-rich nucleus 211Pb. The observation of its Îł decay has allowed identification of excited states up to the highest spin which can be formed from the three valence neutrons, including identification of three high-spin isomers. Level energies and transition strengths are compared to shell-model calculations with empirical interactions and predictions are made for the expected behaviour of more neutron-rich lead isotopes. The evidence for a possible increase in the neutron effective charge moving away from the N=126 shell gap is evaluated
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